FITS to AVIF Converter
Processing entirely on your device — large files may take a moment.
FITS (Flexible Image Transport System) is the data format of professional astronomy — every image carries a human-readable header with telescope, exposure and world coordinates alongside the raw pixel data. AVIF delivers the smallest files at top visual quality for modern websites — it is supported by all current browsers.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How FITS compares to AVIF
| FITS | AVIF | |
|---|---|---|
| Compression | None (optionally Rice/GZIP) | Lossy (AV1), lossless variant |
| Transparency | Not supported | Supported |
| Animation | Not supported | Supported |
| Metadata | Rich text header (WCS) | EXIF, ICC embeddable |
| Best for | Telescope frames, science data | High-performance web images |
How to convert FITS to AVIF
- 1
Select your files
Drag & drop your FITS files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to AVIF". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted AVIF file individually, or grab everything at once as a ZIP archive.
About the FITS format
FITS (Flexible Image Transport System) has carried professional astronomy data since 1981: every file opens with a plain-text header that records telescope, instrument, exposure, filters and world coordinates, followed by raw pixel arrays — often 16-bit or float, sometimes data cubes.
Values can be negative or far above display range, so FITS never looks right in a photo viewer. Converting to PNG applies a simple scaling pass that reveals the nebula or galaxy in the numbers — good for previews, while science pipelines keep the original.
+Strengths
- ✓Self-documenting science headers
- ✓High bit depth (16/32-bit, float)
- ✓The standard of every observatory
!Limitations
- −Not display-ready
- −Files are large and uncompressed
About the AVIF format
AVIF wraps AV1 intra-frame coding inside a HEIF container, championed by Netflix and the Alliance for Open Media. It is currently the compression king of still images: at typical web sizes it beats JPG and WebP visibly, it inherits 10/12-bit color, HDR and wide gamut from its video heritage, and it animates. Being AV1-based, it is royalty-free.
The trade-off is encoding cost: AVIF encoding is genuinely slow in software, which matters for build pipelines and batch jobs. Support is solid in every current browser (Safari since 16.4, Chrome since 85), while many native apps and older photo tools still shrug at it.
+Strengths
- ✓Best-in-class compression at web sizes
- ✓HDR, 10/12-bit color and wide gamut supported
- ✓Royalty-free (AV1) and animation-capable
!Limitations
- −Encoding is slow, especially in software
- −Native app and photo-tool support still maturing
- −No progressive decoding
Why convert FITS to AVIF?
Think of it as moving your file to the container that fits the job. Not display-ready AVIF works differently: Best-in-class compression at web sizes If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this FITS to AVIF converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will converting FITS to AVIF reduce quality?
AVIF uses lossy compression, so a small amount of recompression is unavoidable. The quality slider lets you choose between maximum fidelity and smallest file size — the default is visually indistinguishable for photos.
Can I convert several FITS files at once?
Yes — drop as many files as you like into the tool and they are converted in one batch. When more than one file comes out, everything is bundled into a ZIP for a single download.
Will transparent areas survive the conversion to AVIF?
Transparency is kept whenever AVIF actually supports an alpha channel. If the target format has none (like JPG), transparent areas are flattened onto a white background — that is a property of the format, not of this tool.